Three-dimensional porous structures for bone ingrowth and methods for producing

ABSTRACT

An orthopaedic prosthetic component is provided. The orthopaedic prosthetic component comprises a porous three-dimensional structure shaped to be implanted in a patient&#39;s body. The porous three-dimensional structure comprises a plurality of unit cells. At least one unit cell comprises a first geometric structure having a first geometry and comprising a plurality of first struts, and a second geometric structure having a second geometry and comprising a plurality of second struts connected to a number of the plurality of first struts to form the second geometric structure.

This application claims priority to U.S. Provisional App. No.62/648,353, which was filed on Mar. 26, 2018 and is expresslyincorporated herein by reference.

TECHNICAL FIELD

The embodiments disclosed herein are generally directed towards porousmetal structures and methods for manufacturing them, and, morespecifically, to porous metal structures in medical devices that havegeometric lattice configurations suited to allow for exact control ofporosity and pore size in a porous metal structure.

BACKGROUND

The embodiments disclosed herein are generally directed towardsthree-dimensional porous structures for bone ingrowth and methods forproducing said structures.

The field of rapid prototyping and additive manufacturing has seen manyadvances over the years, particularly for rapid prototyping of articlessuch as prototype parts and mold dies. These advances have reducedfabrication cost and time, while increasing accuracy of the finishedproduct, versus conventional machining processes, such as those wherematerials (e.g., metal) start as a block of material, and areconsequently machined down to the finished product.

However, the main focus of rapid prototyping three-dimensionalstructures has been on increasing density of rapid prototypedstructures. Examples of modern rapid prototyping/additive manufacturingtechniques include sheet lamination, adhesion bonding, laser sintering(or selective laser sintering), laser melting (or selective lasersintering), photopolymerization, droplet deposition, stereolithography,3D printing, fused deposition modeling, and 3D plotting. Particularly inthe areas of selective laser sintering, selective laser melting and 3Dprinting, the improvement in the production of high density parts hasmade those techniques useful in designing and accurately producingarticles such as highly dense metal parts.

In the past few years, some in the additive manufacturing field haveattempted to create solutions that provide the mechanical strength,interconnected channel design, porosity and pore size in porousstructures necessary for application in promoting mammalian cell growthand regeneration. However, the current methods and geometries havelimited control over the pore size distribution, which exerts a stronginfluence on the ingrowth behavior of mammalian cells such as bone.Moreover, the current methods and geometries often fall short inproducing porous structures having unit cell geometries with pore sizesand porosities simultaneously in the range believed to be beneficial foringrowth while maintaining structural integrity during the manufacturingprocess (e.g., 3D printing). As a result, current unit cell geometricstructures must either have a very large pore size or very low porosity.Furthermore, current methods and geometries generally prevent closecorrelation between a selected strut length and diameter of a unit cell,within a structure's geometry, and the resulting geometric featuresdesired in the porous structure.

Current methods of manufacturing porous metal materials for boneingrowth have limited control over the pore size distribution, whichexerts a strong influence on the ingrowth behavior of bone. Bettersimultaneous control of the maximum pore size, minimum pore size, andporosity would enable better bone ingrowth. Additive manufacturingtechniques conceptually enable production of lattice structures withperfect control over the geometry but are practically limited to theminimum lattice strut diameter that the machine can build, and by theneed for any lattice structure to be self-supporting. The minimum strutdiameter for current 3D printers is approximately 200-250 microns, whichmeans that many geometric structures must either have a very large poresize or very low porosity.

SUMMARY

According to one aspect of the disclosure, geometric structures, andcorresponding manufacturing processes, that allow improved simultaneouscontrol of the maximum pore size, minimum pore size, and porosity toenable better bone ingrowth are disclosed. The manufacturing processincludes modifying independent strut lengths and/or diameters to achievedesired geometric features (for example, pore size, porosity, windowsize) in the unit cells of the porous structure. The unit cellgeometries disclosed herein enable smaller pore sizes at higherporosities while providing a more homogenous overall structure (i.e.,smaller gap between pore size and window size). Structures having unitcells with such robust geometries allow the manufacturing of robustporous structures largely independent of the manufacturing technologyused.

According to another aspect, an orthopaedic prosthetic component isdisclosed. The orthopaedic prosthetic component comprises a porousthree-dimensional structure shaped to be implanted in a patient's body.The porous three-dimensional structure comprises a plurality ofconnected unit cells, and at least one unit cell comprises a pluralityof lattice struts and a plurality of internal struts. The at least oneunit cell includes a first geometric structure comprising the pluralityof lattice struts, and a plurality of second geometric structures formedout of the plurality of internal struts within the first geometricstructure and a number of the lattice struts. Each second geometricstructure has an internal volume that is substantially equal to theinternal volumes of the other second geometric structures.

In some embodiments, the porous three-dimensional structure may have aporosity between about 50% and about 75%.

In some embodiments, the orthopaedic prosthetic component may comprise asolid base. The porous three-dimensional structure may be attached tothe solid base. Additionally, in some embodiments, the base may includea platform and a stem extending away from the platform. The stem extendsthrough the porous three-dimension structure.

In some embodiments, the number of the lattice struts and the pluralityof internal struts may define a plurality of openings in the porousthree-dimensional structure. Each opening of the plurality of openingsmay have a window size. The internal volume of each geometric structuremay have a pore size, and the ratio of the pore size of each geometricstructure to the window size of each opening of the geometric structuremay be in a range of 1.00 to 2.90.

In some embodiments, the ratio of the pore size of each geometricstructure to the window size of each opening of the geometric structuremay be in a range of 1.50 to 1.60. Additionally, in some embodiments,the ratio of the pore size of each geometric structure to the windowsize of each opening of the geometric structure may be in a range of1.00 to 1.10.

In some embodiments, the first geometric structure may be a rhombicdodecahedron. Additionally, in some embodiments, each of the pluralityof second geometric structures may be a trigonal trapezohedron. In someembodiments, the plurality of second geometric structures may consist offour trigonal trapezohedrons.

In some embodiments, each of the plurality of second geometricstructures may be an octahedron.

According to another aspect, an orthopaedic prosthetic componentcomprises a porous three-dimensional structure shaped to be implanted ina patient's body, and the porous three-dimensional structure comprises aplurality of unit cells. Each unit cell comprises a first geometricstructure having a first geometry and comprising a plurality of firststruts, and a second geometric structure having a second geometry andcomprising a plurality of second struts connected to a number of theplurality of first struts to form the second geometric structure.

In some embodiments, each second geometric structure may have a poresize, and the number of the lattice struts and the plurality of internalstruts define a plurality of openings in the porous three-dimensionalstructure. Each opening of the plurality of openings may have a windowsize. The ratio of the pore size of each second geometric structure tothe window size of each opening of the second geometric structure may bein a range of 1.00 to 2.90.

In some embodiments, the ratio of the pore size of each second geometricstructure to the window size of each opening of the second geometricstructure may be in a range of 1.50 to 1.60. In some embodiments, theratio of the pore size of each second geometric structure to the windowsize of each opening of the second geometric structure may be in a rangeof 1.00 to 1.10.

In some embodiments, the porous three-dimensional structure may have aporosity that is between about 20% and about 95%.

In some embodiments, the porous three-dimensional structure may have aporosity that is between about 50% and about 75%.

According to another aspect, a method for producing a porousthree-dimensional structure is disclosed. The method comprisesdepositing and scanning successive layers of metal powders with a beamto form a porous three-dimensional structure comprising a plurality ofunit cells and having predetermined geometric properties. Each unit cellcomprises a plurality of lattice struts and a plurality of internalstruts. Each unit cell includes a first geometric structure comprisingthe plurality of lattice struts, and a plurality of second geometricstructures, formed out of the plurality of internal struts within thefirst geometric structure and a number of lattice struts of theplurality of lattice struts.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the principles disclosed herein,and the advantages thereof, reference is now made to the followingdescriptions taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a simplified elevation view of an orthopaedic prostheticcomponent;

FIG. 2 is a simplified perspective view of the orthopaedic prostheticcomponent of FIG. 1;

FIG. 3 is a perspective view of a unit cell of the porous structure ofthe orthopaedic prosthetic component of FIGS. 1-2;

FIG. 4 is a perspective view of one geometric structure of the unit cellof FIG. 3;

FIG. 5 is a simplified perspective view of another geometric structureof the unit cell of FIG. 3;

FIG. 6 is a perspective view of another embodiment of a unit cell of aporous structure for the orthopaedic prosthetic component of FIGS. 1-2;

FIG. 7 is a simplified perspective view of another geometric structureof the unit cell of FIG. 3;

FIG. 8 illustrates a chart of porosity percentage versus strutlength/diameter for various unit cell geometries, in accordance withvarious embodiments;

FIG. 9 illustrates a chart of pore size and minimum pore window openingsize versus porosity percentage for various unit cell geometries, inaccordance with various embodiments;

FIG. 10 illustrates an association of window size to a unit cellstructure, in accordance with various embodiments; and

FIG. 11 illustrates a workflow for producing a porous three-dimensionalstructure, in accordance with various embodiments.

DETAILED DESCRIPTION

This specification describes exemplary embodiments and applications ofthe disclosure. The disclosure, however, is not limited to theseexemplary embodiments and applications or to the manner in which theexemplary embodiments and applications operate or are described herein.Moreover, the figures may show simplified or partial views, and thedimensions of elements in the figures may be exaggerated or otherwisenot in proportion. In addition, as the terms “on,” “attached to,”“connected to,” “coupled to,” or similar words are used herein, oneelement (e.g., a material, a layer, a base, etc.) can be “on,” “attachedto,” “connected to,” or “coupled to” another element regardless ofwhether the one element is directly on, attached to, connected to, orcoupled to the other element, there are one or more intervening elementsbetween the one element and the other element, or the two elements areintegrated as a single piece. Also, unless the context dictatesotherwise, directions (e.g., above, below, top, bottom, side, up, down,under, over, upper, lower, horizontal, vertical, “x,” “y,” “z,” etc.),if provided, are relative and provided solely by way of example and forease of illustration and discussion and not by way of limitation. Inaddition, where reference is made to a list of elements (e.g., elementsa, b, c), such reference is intended to include any one of the listedelements by itself, any combination of less than all of the listedelements, and/or a combination of all of the listed elements. Sectiondivisions in the specification are for ease of review only and do notlimit any combination of elements discussed.

As used herein, “bonded to” or “bonding” denotes an attachment of metalto metal due to a variety of physicochemical mechanisms, including butnot limited to: metallic bonding, electrostatic attraction and/oradhesion forces.

Unless otherwise defined, scientific and technical terms used inconnection with the present teachings described herein shall have themeanings that are commonly understood by those of ordinary skill in theart.

The present disclosure relates to porous three-dimensional metallicstructures and methods for manufacturing them for medical applications.As described in greater detail below, the porous metallic structurespromote hard or soft tissue interlocks between prosthetic componentsimplanted in a patient's body and the patient's surrounding hard or softtissue. For example, when included on an orthopaedic prostheticcomponent configured to be implanted in a patient's body, the porousthree-dimensional metallic structure can be used to provide a porousouter layer of the orthopaedic prosthetic component to form a bonein-growth structure. Alternatively, the porous three-dimensionalmetallic structure can be used as an implant with the requiredstructural integrity to both fulfill the intended function of theimplant and to provide interconnected porosity for tissue interlock(e.g., bone in-growth) with the surrounding tissue. In variousembodiments, the types of metals that can be used to form the porousthree-dimensional metallic structures can include, but are not limitedto, titanium, titanium alloys, stainless steel, cobalt chrome alloys,tantalum or niobium.

Referring now to FIGS. 1 and 2, an orthopaedic implant or prostheticcomponent 100 is illustrated. The prosthetic component 100 includes abase 110, a porous three-dimensional structure or layer 120, and a coneor stem 130 extending away from the base 110. In the illustrativeembodiment, the porous structure 120 surrounds a portion of the base 110and a portion of the stem 130. It should be appreciated that the porousstructure 120 can be provided as a layer separate from the base 110and/or the stem 130. The porous structure 120 may also be provided as acoating that surrounds all of the base 110 and/or all of the stem 130.As described in greater detail below, the porous structure includes aplurality of unit cells that define voids or spaces that permit theingrowth of bone, thereby promoting fixation of the prosthetic component100 to a patient's bone.

The orthopaedic implant 100 may be implanted into a tibial bone. Forexample, the stem 130 can be inserted into the tibial bone, with a ledgeportion 140 of implant 100 resting against a proximal portion of thetibial bone. It should be appreciated that the various porous structuresdescribed herein may be incorporated into various orthopaedic implantdesigns, including, for example, a tibial prosthetic component or afemoral prosthetic component similar to the tibial and femoralcomponents shown in U.S. Pat. No. 8,470,047, which is expresslyincorporated herein by reference. The porous structures may also beincluded in other orthopaedic implant designs, including a patellacomponent shaped to engage a femoral prosthetic component and prostheticcomponents for use in a hip or shoulder arthroplasty surgery

It should also be noted, for the preceding and going forward, that thebase 110 can be any type of structure capable of, for example,contacting, supporting, connecting to or with, or anchoring to or withcomponents of various embodiments herein. The base 110 can include, forexample, a metal or non-metal tray, a metal or non-metal baseplate, ametal or non-metal structure that sits on a tray, and so on. The typesof metal that can be used to form the base 110 include, but are notlimited to, titanium, titanium alloys, stainless steel, cobalt chromealloys, tantalum or niobium.

In the illustrative embodiment, the stem 130 includes a solid region150, which is coated by a porous region 160 of the porous structure 120.The solid region 150 of the stem 130 is anchored to the base 110 andextends outwardly from the porous structure 120 such that the porousstructure 120 surrounds the region of stem 130 proximal to base 110. Inother embodiments, the stem 130 may be anchored to the porous structure120. The types of metal that can be used to form the stem 130 include,but are not limited to, titanium, titanium alloys, stainless steel,cobalt chrome alloys, tantalum or niobium.

Referring now to FIG. 3, the porous structure 120 of the implant 100includes a plurality of connected unit cells, and each unit cellillustratively has the unit cell structure 200 shown in FIG. 3. Thetypes of metal that can be used to form the unit cell structures shownin include, but are not limited to, titanium, titanium alloys, stainlesssteel, cobalt chrome alloys, tantalum or niobium. As shown in FIG. 3,each structure 200 includes a plurality of lattice struts 210 and aplurality of internal struts 220, which form a first geometric structure230 and a plurality of second geometric structures 240 that are withinthe first geometric structure 230. In the illustrative embodiment, thefirst geometric structure 230 comprises the plurality of lattice struts210. As shown in FIG. 4, the plurality of lattice struts 210 cooperateto form a rhombic dodecahedron.

Each of the plurality of second geometric structures 240 has an internalvolume 250 that is substantially equal to the internal volumes 250 ofthe other second geometric structures 240. As shown in FIG. 5, eachsecond geometric structure 240 is formed by a number of internal struts220 and a number of lattice struts 210. Each second geometric structure240 is illustratively a trigonal trapezohedron. As illustrated in FIG.3, the plurality of second geometric structures 240 within the firstgeometric structure 230 include four trigonal trapezohedrons such thatthe unit cell structure 200 is a rhombic trigonal trapezohedron.

It should be appreciated that each unit cell structure may include othertypes of second geometric structures. For example, as shown in FIG. 6, aunit cell structure 300 includes a plurality of lattice struts 310 and aplurality of internal struts 320, which form a first geometric structure330 and a plurality of second geometric structures 340 that are withinthe first geometric structure 330. In the illustrative embodiment, thefirst geometric structure 330, like the first geometric structure 230,comprises the plurality of lattice struts 310 and is a rhombicdodecahedron.

As shown in FIG. 7, each second geometric structure 340 is formed by anumber of internal struts 320 and a number of lattice struts 310. Eachsecond geometric structure 340 is illustratively an octahedron (e.g., adiamond-shaped structure). As illustrated in FIG. 6, the plurality ofsecond geometric structures 340 within the first geometric structure 330include six octahedrons such that the unit cell structure 300 is arhombic octahedron.

Within the unit cell structures of the porous three-dimensionalstructure described above, at least one of a length and diameter of atleast one strut within each unit cell can be modified to meetpredetermined or desired geometric properties of the lattice. Thesegeometric properties can be selected from the group consisting ofporosity, pore size, minimum window size, and combinations thereof. Itwas advantageously discovered that certain geometric structures(discussed below) of the unit cell structure could optimize one or moreof these geometric properties to provide a more robust, and homogenous,geometry. The resulting geometry provides for more optimal bone ingrowthwhile maintaining the requisite porous structure stability.

Turning to porosity, the porous structure 120 has a porosity of betweenabout 50% and about 75%. As used herein, the term “about” refers to arange associated with typical manufacturing tolerances. In that way, aporosity of “about 50%” may be porosity of 50% plus or minus a typicalmanufacturing tolerance such as, for example, 2% (i.e., a range of 48%to 52%). In other embodiments, the porosity of the porousthree-dimensional structure is between about 20% and about 95%. In otherembodiments, the porosity is in a range of between about 35% and about85%. Geometrically, the porosity of the unit cell structure is dependenton the ratio of the strut length (a) to the strut diameter (d). FIG. 8,for example, a chart 800 of porosity percentage versus strutlength/diameter for various unit cell geometries is provided, inaccordance with various embodiments. As outlined in the chart 800, threeparticular unit cell geometries/structures were examined, namely arhombic dodecahedron (RD) (see, e.g., FIG. 4), a rhombic dodecahedronprovided with four internal struts (RD+4) (or rhombic trigonaltrapezohedron) (see, e.g., FIG. 3), and a rhombic dodecahedron providedwith eight internal struts (RD+8) (or rhombic octahedron) (see, e.g.,FIG. 6). For each of the structures, porosities were obtained at severala/d ratios from a design file for each unit cell structure and therelationship for each unit cell structure modeled by fitting the data toa fourth order polynomial equation of the form:

Porosity=A*(a/d)⁴ +B*(a/d)³ +C*(a/d)² +D*(a/d)+E   (1)

Wherein A, B, C, D, and E are constants. In this comparison, thestructure dimensions were derived geometrically from the strut lengthand diameter of each unit cell structure.

As observed in the chart 800 of FIG. 8, the RD structure generallypossesses a greater porosity at a given a/d ratio, which is to beexpected given its lack of internal struts compared to the RD+4 and RD+8structures. The porosity for the RD structure is illustrated by the line802. However, this decrease in porosity in the RD+4 and RD+8 structures,illustrated by lines 804, 806, respectively, enables designs made withthem to reach combinations of relatively lower porosity, lower poresize, and relatively higher window size at a constant strut diameter(fixed by the build resolution of the printer) not possible with the RD,as described in greater detail below.

Referring now to FIG. 9, a chart 900 of pore size and minimum windowsize versus porosity percentage for various unit cellgeometries/structures is provided, in accordance with variousembodiments. As in FIG. 8, three particular unit cell structures wereexamined, namely a rhombic dodecahedron (RD) (see, e.g., FIG. 4), arhombic dodecahedron provided with four internal struts (RD+4) (orrhombic trigonal trapezohedron) (see, e.g., FIG. 3), and a rhombicdodecahedron provided with eight internal struts (RD+8) (or rhombicoctahedron) (see, e.g., FIG. 6). The pore size of the rhombicdodecahedron, for example, was taken as the equivalent diameter of asphere within the volume bounded within the rhombic dodecahedron unitcell, and the volume was calculated by taking the volume of the rhombicdodecahedron of strut length (a) and subtracting the volume of eachstrut within or bounded by the rhombic dodecahedron. The equationsprovided herein for calculating pore size (PS) depend on the strutlength (a), diameter (d), and porosity in decimal units (p). Theequations are as follows:

For the RD structure:

$\begin{matrix}{{PS} = {a*\sqrt[3]{6\text{/}\pi}*\sqrt[3]{\frac{16*\sqrt{3}*p}{9} - {\frac{4d}{a}*\left( {1 - \frac{\sqrt{2}d}{2a}} \right)^{2}}}}} & (2)\end{matrix}$

For the RD+4 structure:

$\begin{matrix}{{PS} = \sqrt[3]{\frac{6}{4\pi}*\left\lbrack {{\left( {1 - \left\{ {1 - p} \right\}} \right)*\left( {\frac{16}{9}*\sqrt[2]{3}*a^{3}} \right)} - {0.5*\left( {{\pi*d^{2}*\left\{ {{\sqrt[2]{3}*a} - {0.75*d}} \right\}} - {d^{3}*\left\{ {4 - {2\sqrt[2]{2}}} \right\}}} \right)}} \right\rbrack}} & (3)\end{matrix}$

For the RD+8 structure:

$\begin{matrix}{{PS} = \sqrt[3]{\frac{6}{8\pi}*\left\lbrack {{\left( {1 - \left\{ {1 - p} \right\}} \right)*\left( {\frac{16}{9}*\sqrt[2]{3}*a^{3}} \right)} - {\pi*d^{2}*\left\{ {{2a} - d} \right\}} + {4.5d^{3}*\left\{ {{2\sqrt[2]{2}} - \sqrt[2]{6}} \right\}}} \right\rbrack}} & (4)\end{matrix}$

The line 902 in the chart 900 illustrates the relationship between poresize and porosity percentage for the rhombic dodecahedron (RD). The line904 illustrates the relationship between pore size and porositypercentage for the rhombic trigonal trapezohedron (RD+4), and the line906 illustrates the relationship between pore size and porositypercentage for the rhombic octahedron (RD+8).

As observed in the chart 900 of FIG. 9, at lower porosity percentages,the three structures generally provided similar required pore sizes.However, as the given porosity percentage increases (and assuming thatthe strut diameters remain substantially the same), the required poresize in the RD structure to accommodate the porosity percentage becomessignificantly greater than the other structures, thus putting morestringent requirements on the RD structure as required porosityincreases by causing the pore size to increase to beyond what may beeffective for bone in-growth. In other words, as required porositypercentage increases, the less effective the RD structure becomes, whichis noteworthy when designing porous three-dimensional structures such asthose discussed herein.

Referring now to FIG. 10, each unit cell structure 200 has a pluralityof outer faces 1002 and the lattice struts 210 cooperate to define anumber of openings 1004 in the outer faces 1002. The internal struts 220of the unit cell structure 200 cooperate with a number of lattice struts210 to form a number of internal openings 1006. The minimum windowopening or size of each of the openings 1004, 1006 may be defined as thediameter 1008 of a circle 1010 positioned in the corresponding opening(illustratively one of the openings 1004 in FIG. 10) such that eachstrut 210 (or strut 220) is positioned on a tangent line of the circle1010. The lengths and diameters of the struts thereby determine the sizeof each of the openings 1004, 1006 and, by extension, the diameter ofthe largest sphere that can fit therein. For example, for a given strutlength, as the strut diameter increases, the minimum window openingwould decrease.

These associations are provided by the following equation, which wasused to calculate minimum window opening for all structures (e.g., RD,RD+4, RD+8, etc.) and generate the lines 908, 910, 912 in FIG. 9:

m=2/3√{square root over (2)}*a−d   (5)

For the purposes of the chart 900, the minimum window opening is thediameter of the largest circle 1010 that can fit in each opening. Inother words, it is the diameter of the inscribed circle and, as such, isdependent on the strut length (a) and diameter (d). The relationshipbetween window size versus porosity percentage for various unit cellgeometries. The line 908 in the chart 900 illustrates the relationshipbetween minimum window opening versus porosity for the rhombicdodecahedron (RD). The line 910 illustrates the relationship betweenminimum window opening versus porosity for the rhombic trigonaltrapezohedron (RD+4), and the line 912 illustrates the relationshipbetween minimum window opening versus porosity for the rhombicoctahedron (RD+8).

As observed on the chart 900 in FIG. 9, at generally all porositypercentages, there exists a generally uniform gap in the minimum windowopening for between each unit cell structure. As such, regardless ofrequired porosity percentage for a given porous three-dimensionalstructure with a substantially constant strut diameter, the RD+8structure will possess a greater minimum window opening than the RD+4and RD structures, and both the RD+8 and RD+4 structures will possess agreater minimum window opening than the RD structure, to a givenporosity percentage.

The results in FIG. 9 establish that the structures having internalstruts, namely RD+4, and to a lesser extent RD+8, are advantageous overthe RD structure. The RD+4 and RD+8 enable smaller pore size at a givenporosity and strut diameter. Whatever advantage the RD structure wouldseem to have in porosity as a function of a/d ratio almost entirelydiminishes as the required a/d ratio increases. Finally, the RD+4 andRD+8 structures (or structures with internal struts) provide the mosthomogenous structure by providing a smaller difference between pore sizeand window size than the RD structure.

In the porous structure 120, the ratio of the pore size of a unit cellto any of its corresponding window sizes is in a range of 1.50 to 1.60.In other embodiments, the ratio may be in a range of 1.00 to 1.10. Instill other embodiments, the ratio may be 1.00 to 2.90. As shown in FIG.9, the difference between pore size and window size is substantiallyless for the RTT structure of FIGS. 3 and 6 than the RD structure. As aconsequence, the RTT structure advantageously provides for a morehomogeneous structure, with a smaller difference between the pore windowsize and overall pore size, especially at high levels of porosity, whichpromotes bone in-growth by providing window sizes closely in proportionof the pore size. Though only RTT is referenced in this figure, theconclusion would hold for various structures that include internalstruts, for example, structures with internal struts in multiples offour.

In accordance with various embodiments, an orthopaedic implant isprovided. The implant can include a porous three-dimensional structurecomprising a lattice of connected unit cells, as illustrated, forexample, by the unit cell structure of FIGS. 3-5. The at least one unitcell can comprise a plurality of lattice struts. The at least one unitcell can further comprise a first geometric structure comprising theplurality of lattice struts, and a second geometric structure sharing asubset of the plurality of lattice struts of the first geometricstructure and having a different geometry from the first geometricstructure (see FIGS. 3 and 6). Further, at least a portion of the subsetof the plurality of lattice struts in the second geometric structure canintersect to form angles substantially equal to the angles formed byintersections of the plurality of lattice struts of the first geometricstructure.

As discussed above, the first geometric structure can be a rhombicdodecahedron as illustrated, for example, in FIG. 4. The secondgeometric structure can be a trigonal trapezohedron (see FIG. 5). Thetrigonal trapezohedron can be formed by inserting four struts into thefirst geometric structure as illustrated, for example, in FIG. 3.Further, the at least one unit cell can include four trigonaltrapezohedron geometric structures within the first geometric structureas illustrated, for example, in FIG. 3.

Within the porous three-dimensional structure, at least one of a lengthand diameter of at least one strut within the lattice can be modified tomeet predetermined geometric properties of the lattice. As discussedabove, these geometric properties can be selected from the groupconsisting of, porosity, pore size, minimum opening size, andcombinations thereof. For example, the porosity can be between about 20%and about 95%. The porosity can also be between about 35% and about 85%.The porosity can also be between about 50% and about 75%. Further, theindividual strut lengths can be modified to be, for example, about 25%to about 175% of the average strut length of the plurality of struts.The individual lattice strut lengths can also be modified to be, forexample, about 50% to about 150% of the average strut length of theplurality of lattice struts. The individual lattice strut lengths canalso be modified to be, for example, about 75% to about 125% of theaverage strut length of the plurality of lattice struts.

In accordance with various embodiments, an orthopaedic implant isprovided. The implant can include a porous three-dimensional structurecomprising a plurality of repeating unit cells, with each unit cellcomprising a plurality of struts. Each unit cell can include a basegeometric structure, and a secondary geometric structure formed out of aportion of the base geometric structure and having a different geometryfrom the base geometric structure. Further, for a given porousthree-dimensional structure porosity, at least one unit cell can have apore size that is different from the average geometric structure poresize of the porous three-dimensional structure and a window size that isdifferent from the average geometric structure window size of the porousthree-dimensional structure.

Within the porous three-dimensional structure, at least one of a lengthand diameter of at least one strut within the unit cell can be modifiedto meet predetermined geometric properties of the unit cell. Asdiscussed above, the geometric properties can be selected from the groupconsisting of, porosity, pore size, minimum opening size, andcombinations thereof. For example, the porosity can be between about 20%and about 95%. The porosity can also be between about 35% and about 85%.The porosity can also be between about 50% and about 75%. Moreover,strut lengths can be modified to be about 25% to about 175% of theaverage strut length of the plurality of struts. The individual latticestrut lengths can also be modified to be, for example, about 50% toabout 150% of the average strut length of the plurality of latticestruts. The individual lattice strut lengths can also be modified to be,for example, about 75% to about 125% of the average strut length of theplurality of lattice struts.

As discussed above, the first geometric structure can be a rhombicdodecahedron. The second geometric structure can be a trigonaltrapezohedron. The trigonal trapezohedron can be formed by insertingfour struts into the first geometric structure. Further, the at leastone unit cell can include four trigonal trapezohedron geometricstructures within the first geometric structure.

In accordance with various embodiments, an orthopaedic implant isprovided. The implant can include a porous three-dimensional structurecomprising a plurality of unit cells. Each unit cell can comprise anouter geometric structure having a first geometry and comprising aplurality of first struts. Each unit cell can further comprise an innergeometric structure having a second geometry and further comprise aplurality of second struts connected to a portion of the plurality offirst struts to form the inner geometric structure within the outergeometric structure.

In accordance with various embodiments, the outer geometric structurecan be a rhombic dodecahedron. The inner geometric structure can be atrigonal trapezohedron. The trigonal trapezohedron can be formed byinserting four struts into the outer geometric structure. Further, theat least one unit cell can include four trigonal trapezohedron geometricstructures within the outer geometric structure.

Manufacturing Processes

The porous three-dimensional metallic structures disclosed above can bemade using a variety of different metal component manufacturingtechniques, including but not limited to: Casting Processes (castingprocesses involve pouring molten metal into a mold cavity where, oncesolid, the metal can take on the shape of the cavity. Examples include,expendable mold casting, permanent mold casting, and powder compactionmetallurgy), Deformation Processes (deformation processes include metalforming and sheet metalworking processes which involve the use of a toolthat applies mechanical stresses to metal which exceed the yield stressof the metal), Material Removal Processes (these processes remove extramaterial from the workpiece in order to achieve the desired shape.Examples of material removal processes include, tool machining andabrasive machining), and Additive Manufacturing Processes (theseprocesses involve the use of digital 3D design data to build up a metalcomponent up in layers by depositing successive layers of material).Additive Manufacturing Processes can include, only by way of example,powder bed fusion printing method (e.g., melting and sintering), coldspray 3D printing, wire feed 3D printing, fused deposition 3D printing,extrusion 3D printing, liquid metal 3D printing, stereolithography 3Dprinting, binder jetting 3D printing, material jetting 3D printing, andso on. It should be appreciated, however, that additive manufacturingprocesses offer some unique advantages over the other metal componentmanufacturing techniques with respect to the manufacture of porousthree-dimensional metallic structures (disclosed above) due to thecomplexities of the geometries and structural elements of the unit cellswhich comprise those types of structures.

In accordance with various embodiments, a method for producing a porousthree-dimensional structure is provided, for example, by method 1100illustrated in FIG. 11. The method can comprise depositing and scanningsuccessive layers of metal powders with a beam to form a porousthree-dimensional structure. The porous three-dimensional structure cancomprise a plurality of unit cells having predetermined geometricproperties, and each unit cell can comprise a plurality of latticestruts and a plurality of internal struts. Each unit cell furtherincludes a first geometric structure comprising the plurality of latticestruts and a plurality of second geometric structures, formed out of theplurality of internal struts within the first geometric structure. Thebeam (or scanning beam) can be an electron beam. The beam (or scanningbeam) can be a laser beam.

As provided in FIG. 11, the method 1100 may begin with a step 1110,which includes depositing a layer of metal powder. The method maycontinue with a step 1120, which includes scanning a layer of metalpowder. As provided in a step 1130, the steps 1110 and 1120 are repeateduntil a porous three-dimensional structure is formed comprising aplurality of unit cells having predetermined geometric properties. Eachunit cell comprises a plurality of lattice struts and a plurality ofinternal struts. Each unit cell including a first geometric structurecomprising the plurality of lattice struts, and a plurality of secondgeometric structures formed out of a number of internal struts withinthe first geometric structure and a number of lattice struts.

Regarding the various methods described herein, the metal powders can besintered to form the porous three-dimensional structure. Alternatively,the metal powders can be melted to form the porous three-dimensionalstructure. The successive layers of metal powders can be deposited ontoa solid base (see above for discussion regarding base). In variousembodiments, the types of metal powders that can be used include, butare not limited to, titanium, titanium alloys, stainless steel, cobaltchrome alloys, tantalum or niobium powders.

Regarding the various methods described herein, the geometric propertiescan be selected from the group consisting of, porosity, pore size,minimum opening size, and combinations thereof. The porosity can bebetween about 20% and about 95%. The porosity can also be between about40% and about 80%. The porosity can also be between about 50% and about75%. Moreover, strut lengths can be modified to be about 25% to about175% of the average strut length of the plurality of struts. Theindividual lattice strut lengths can also be modified to be, forexample, about 50% to about 150% of the average strut length of theplurality of lattice struts. The individual lattice strut lengths canalso be modified to be, for example, about 75% to about 125% of theaverage strut length of the plurality of lattice struts. Further, theunit cell can have a pore size less than the first geometric structurepore size. Moreover, the unit cell can have a window size greater thanthe window size of each of the plurality of second geometric structures.

Regarding the various methods described, the first geometric structurecan be a rhombic dodecahedron. Each of the second geometric structurescan be a trigonal trapezohedron. The trigonal trapezohedron can beformed by inserting four struts into the first geometric structure.Further, the at least one unit cell can include four trigonaltrapezohedron geometric structures within the first geometric structure.

In various embodiments, a method for producing a porousthree-dimensional structure is provided, the method comprising applyinga stream of metal particles at a predetermined velocity onto a base toform a porous three-dimensional structure comprising a plurality of unitcells and having predetermined geometric properties, each unit cellcomprising a plurality of lattice struts and a plurality of internalstruts. Each unit cell can include, a first geometric structurecomprising the plurality of lattice struts, and a plurality of secondgeometric structures, formed out of the plurality of internal strutswithin the first geometric structure. In various embodiments, the typesof metal particles that can be used include, but are not limited to,titanium, titanium alloys, stainless steel, cobalt chrome alloys,tantalum or niobium particles.

The predetermined velocity can be a critical velocity required for themetal particles to bond upon impacting the base. The critical velocityis greater than 340 m/s.

The method can further include applying a laser at a predetermined powersetting onto an area of the base where the stream of metal particles isimpacting

The first geometric structure can be a rhombic dodecahedron. In someembodiments, each of the second geometric structures can be a trigonaltrapezohedron. That is, four trigonal trapezohedrons can be formed byinserting four struts into the first geometric structure. In someembodiments, octahedrons can be formed, for example, by inserting eightinternal struts into a first geometric structure. In this case, sixoctahedron geometric structures can be provided within the firstgeometric structure.

In accordance with various embodiments, a method for producing a porousthree-dimensional structure is provided, the method comprisingintroducing a continuous feed of metal wire onto a base surface andapplying a beam at a predetermined power setting to an area where themetal wire contacts the base surface to form a porous three-dimensionalstructure comprising a plurality of unit cells and having predeterminedgeometric properties. Each unit cell can comprise a plurality of latticestruts and a plurality of internal struts, each unit cell including afirst geometric structure comprising the plurality of lattice struts,and a plurality of second geometric structures, formed out of theplurality of internal struts within the first geometric structure. Thebeam (or scanning beam) can be an electron beam. The beam (or scanningbeam) can be a laser beam. In various embodiments, the types of metalwire that can be used include, but are not limited to, titanium,titanium alloys, stainless steel, cobalt chrome alloys, tantalum orniobium wire.

The first geometric structure can be a rhombic dodecahedron. In someembodiments, each of the second geometric structures can be a trigonaltrapezohedron. That is, four trigonal trapezohedrons can be formed byinserting four struts into the first geometric structure. In someembodiments, octahedrons can be formed, for example, by inserting eightinternal struts into a first geometric structure. That is, sixoctahedron geometric structures can be provided within the firstgeometric structure.

In accordance with various embodiments, a method for producing a porousthree-dimensional structure is provided, the method comprisingintroducing a continuous feed of a polymer material embedded with metalelements onto a base surface. The method can further comprise applyingheat to an area where the polymer material contacts the base surface toform a porous three-dimensional structure comprising a plurality of unitcells and having predetermined geometric properties. Each unit cell cancomprise a plurality of lattice struts and a plurality of internalstruts. Each unit cell includes a first geometric structure comprisingthe plurality of lattice struts, and a plurality of second geometricstructures, formed out of a number of the internal struts within thefirst geometric structure and a number of lattice struts. The metalelements can be a metal powder. In various embodiments, the continuousfeed of the polymer material can be supplied through a heated nozzlethus eliminating the need to apply heat to the area where the polymermaterial contacts the base surface to form the porous three-dimensionalstructure. In various embodiments, the types of metal elements that canbe used to embed the polymer material can include, but are not limitedto, titanium, titanium alloys, stainless steel, cobalt chrome alloys,tantalum or niobium.

The method can further comprise scanning the porous three-dimensionalstructure with a beam to burn off the polymer material. The beam (orscanning beam) can be an electron beam. The beam (or scanning beam) canbe a laser beam.

The first geometric structure can be a rhombic dodecahedron. In variousembodiments, each of the second geometric structures can be a trigonaltrapezohedron. That is, four trigonal trapezohedrons can be formed byinserting four struts into the first geometric structure. In variousembodiments, octahedrons can be formed, for example, by inserting eightinternal struts into a first geometric structure. That is, sixoctahedron geometric structures can be provided within the firstgeometric structure.

In accordance with various embodiments, a method for producing a porousthree-dimensional structure is provided, the method comprisingintroducing a metal slurry through a nozzle onto a base surface to forma porous three-dimensional structure comprising a plurality of unitcells and having predetermined geometric properties. Each unit cell cancomprise a plurality of lattice struts and a plurality of internalstruts. Each unit cell can include a first geometric structurecomprising the plurality of lattice struts, and a plurality of secondgeometric structures, formed out of a number of the internal strutswithin the first geometric structure and a number of the lattice struts.In various embodiments, the nozzle is heated at a temperature requiredto bond metallic elements of the metal slurry to the base surface. Invarious embodiments, the metal slurry is an aqueous suspensioncontaining metal particles along with one or more additives (liquid orsolid) to improve the performance of the manufacturing process or theporous three-dimensional structure. In various embodiments, the metalslurry is an organic solvent suspension containing metal particles alongwith one or more additives (liquid or solid) to improve the performanceof the manufacturing process or the porous three-dimensional structure.In various embodiments, the types of metal particles that can beutilized in the metal slurry include, but are not limited to, titanium,titanium alloys, stainless steel, cobalt chrome alloys, tantalum orniobium particles.

The first geometric structure can be a rhombic dodecahedron. In someembodiments, each of the second geometric structures can be a trigonaltrapezohedron. That is, four trigonal trapezohedrons can be formed byinserting four struts into the first geometric structure. In variousembodiments, octahedrons can be formed, for example, by inserting eightinternal struts into a first geometric structure. That is six octahedrongeometric structures can be provided within the first geometricstructure.

In accordance with various embodiments, a method for producing a porousthree-dimensional structure is provided, the method comprisingintroducing successive layers of molten metal onto a base surface toform a porous three-dimensional structure comprising a plurality of unitcells and having predetermined geometric properties. Each unit cell cancomprise a plurality of lattice struts and a plurality of internalstruts. Each unit cell can include a first geometric structurecomprising the plurality of lattice struts, and a plurality of secondgeometric structures, formed out of the plurality of internal strutswithin the first geometric structure and a number of the lattice struts.Further, the molten metal can be introduced as a continuous stream ontothe base surface. The molten metal can also be introduced as a stream ofdiscrete molten metal droplets onto the base surface. In variousembodiments, the types of molten metals that can be used include, butare not limited to, titanium, titanium alloys, stainless steel, cobaltchrome alloys, tantalum or niobium.

The first geometric structure can be a rhombic dodecahedron. In variousembodiments, each of the second geometric structures can be a trigonaltrapezohedron. That is, four trigonal trapezohedrons can be formed byinserting four struts into the first geometric structure. In variousembodiments, octahedrons can be formed, for example, by inserting eightinternal struts into a first geometric structure. That is, sixoctahedron geometric structures can be provided within the firstgeometric structure.

In accordance with various embodiments, a method for producing a porousthree-dimensional structure is provided, the method comprising applyingand photoactivating successive layers of photosensitive polymer embeddedwith metal elements onto a base surface to form a porousthree-dimensional structure comprising a plurality of unit cells andhaving predetermined geometric properties. Each unit cell can comprise aplurality of lattice struts and a plurality of internal struts. Eachunit cell can include a first geometric structure comprising theplurality of lattice struts, and a plurality of second geometricstructures, formed out of the plurality of internal struts within thefirst geometric structure and a number of the lattice struts. In variousembodiments, the types of metal elements that can be used to embed thepolymer material can include, but are not limited to, titanium, titaniumalloys, stainless steel, cobalt chrome alloys, tantalum or niobium.

The first geometric structure can be a rhombic dodecahedron. In someembodiments, each of the second geometric structures can be a trigonaltrapezohedron. That is, four trigonal trapezohedrons can be formed byinserting four struts into the first geometric structure. In someembodiments, octahedrons can be formed, for example, by inserting eightinternal struts into a first geometric structure. That is, sixoctahedron geometric structures can be provided within the firstgeometric structure.

In accordance with various embodiments, a method for producing a porousthree-dimensional structure is provided, the method comprisingdepositing and binding successive layers of metal powders with a bindermaterial to form a porous three-dimensional structure comprising aplurality of unit cells and having predetermined geometric properties.Each unit cell can comprise a plurality of lattice struts and aplurality of internal struts. Each unit cell can include a firstgeometric structure comprising the plurality of lattice struts, and aplurality of second geometric structures, formed out of the plurality ofinternal struts within the first geometric structure and a number of thelattice struts. In various embodiments, the types of metal powders thatcan be used include, but are not limited to, titanium, titanium alloys,stainless steel, cobalt chrome alloys, tantalum or niobium powders.

The method can further include sintering the bound metal powder with abeam. The beam (or scanning beam) can be an electron beam. The beam (orscanning beam) can be a laser beam.

The method can further include melting the bound metal powder with abeam. The beam (or scanning beam) can be an electron beam. The beam (orscanning beam) can be a laser beam.

The first geometric structure can be a rhombic dodecahedron. In someembodiments, each of the second geometric structures can be a trigonaltrapezohedron. That is, four trigonal trapezohedrons can be formed byinserting four struts into the first geometric structure. In someembodiments, octahedrons can also be formed, for example, by insertingeight internal struts into a first geometric structure. That is, sixoctahedron geometric structures can be provided within the firstgeometric structure.

In accordance with various embodiments, a method for producing a porousthree-dimensional structure is provided, the method comprisingdepositing droplets of a metal material onto a base surface, andapplying heat to an area where the metal material contacts the basesurface to form a porous three-dimensional structure comprising aplurality of unit cells and having predetermined geometric properties.Each unit cell can comprise a plurality of lattice struts and aplurality of internal struts. Each unit cell can include a firstgeometric structure comprising the plurality of lattice struts, and aplurality of second geometric structures, formed out of the plurality ofinternal struts within the first geometric structure and a number of thelattice struts. The beam (or scanning beam) can be an electron beam. Thebeam (or scanning beam) can be a laser beam. In various embodiments, thetypes of metal materials that can be used include, but are not limitedto, titanium, titanium alloys, stainless steel, cobalt chrome alloys,tantalum or niobium.

The deposited droplets of metal material can be a metal slurry embeddedwith metallic elements. The metal material can be a metal powder.

The first geometric structure can be a rhombic dodecahedron. In someembodiments, each of the second geometric structures can be a trigonaltrapezohedron. That is, four trigonal trapezohedrons can be formed byinserting four struts into the first geometric structure. In someembodiments, octahedrons can be formed, for example, by inserting eightinternal struts into a first geometric structure. That is, sixoctahedron geometric structures can be provided within the firstgeometric structure.

Although specific embodiments and applications of the same have beendescribed in this specification, these embodiments and applications areexemplary only, and many variations are possible.

While the present teachings are described in conjunction with variousembodiments, it is not intended that the present teachings be limited tosuch embodiments. On the contrary, the present teachings encompassvarious alternatives, modifications, and equivalents, as will beappreciated by those of skill in the art.

Further, in describing various embodiments, the specification may havepresented a method and/or process as a particular sequence of steps.However, to the extent that the method or process does not rely on theparticular order of steps set forth herein, the method or process shouldnot be limited to the particular sequence of steps described. As one ofordinary skill in the art would appreciate, other sequences of steps maybe possible. Therefore, the particular order of the steps set forth inthe specification should not be construed as limitations on the claims.In addition, the claims directed to the method and/or process should notbe limited to the performance of their steps in the order written, andone skilled in the art can readily appreciate that the sequences may bevaried and still remain within the spirit and scope of the variousembodiments.

1-20. (canceled)
 21. An orthopaedic prosthetic component, comprising: aporous three-dimensional structure shaped to be implanted in a patient'sbody, the porous three-dimensional structure comprising a plurality ofconnected unit cells, wherein at least one unit cell of the plurality ofunit cells includes: a first structure comprising a plurality of latticestruts, and a plurality of second structures formed out of a respectiveplurality of internal struts within the first structure and a respectivenumber of the lattice struts, wherein the lattice struts define anaverage lattice strut length, and at least some of the lattice strutsdefine respective lengths that are modified to be different than theaverage lattice strut length and within 50% to 150% of the averagelattice strut length, wherein the lattice struts are arranged such thatthe first structure approximates a rhombic dodecahedron.
 22. Theorthopaedic prosthetic component of claim 21, wherein: the respectivenumber of the lattice struts and the respective plurality of internalstruts of the second structures define respective pluralities ofopenings in the porous three-dimensional structure, each opening of theplurality of openings having a window size, each second structure has arespective internal volume that, in turn, has a respective pore size,and for each second structure, a ratio of the respective pore size toeach window size is in a range of 1.00 to 2.90.
 23. The orthopaedicprosthetic component of claim 22, wherein the ratio is in a range of1.50 to 1.60.
 24. The orthopaedic prosthetic component of claim 22,wherein the ratio is in a range of 1.00 to 1.10.
 25. The orthopaedicprosthetic component of claim 21, wherein the porous three-dimensionalstructure has a porosity between about 50% and about 75%.
 26. Theorthopaedic prosthetic component of claim 21, further comprising a solidbase, wherein the porous three-dimensional structure is attached to thesolid base.
 27. The orthopaedic prosthetic component of claim 24,wherein the solid base includes a platform and a stem extending awayfrom the platform, the stem extending through the porousthree-dimensional structure.
 28. The orthopaedic prosthetic component ofclaim 21, wherein each of the plurality of second structuresapproximates a trigonal trapezohedron.
 29. The orthopaedic prostheticcomponent of claim 21, wherein each of the plurality of secondstructures approximates an octahedron.
 30. The orthopaedic prostheticcomponent of claim 21, wherein the plurality of second structuresconsists of four approximated trigonal trapezohedrons.
 31. Theorthopaedic prosthetic component of claim 21, wherein the respectivelengths of the at least some of the lattice struts are within 75% to125% of the average lattice strut length.
 32. The orthopaedic prostheticcomponent of claim 21, wherein each unit cell of the plurality of unitcells includes: a respective first structure comprising a respectiveplurality of lattice struts, and a respective plurality of secondstructures formed out of a respective plurality of internal strutswithin the respective first structure and a respective number of therespective plurality of lattice struts, wherein the lattice struts ofeach respective plurality of lattice struts define a respective averagelattice strut length, and at least some of the lattice struts of eachrespective plurality of lattice struts define respective lengths thatare modified to be different than the respective average lattice strutlength and within 50% to 150% of the respective average lattice strutlength, wherein the respective lattice struts are arranged such thateach respective first structure approximates a rhombic dodecahedron.